For example, if you want to draw a two level house on a slope like the one attached to this post, you could draw a room that surrounds the garage like the green room in the following image.
If you don't know how to draw a room with a hole, look at this video or draw two rooms which won't include the house surface.
Then, if you select this room and the path to the garage to build a terrain from them with the plug-in, you can design a slope which will show the hole of the garage.
After a few tries, you'll get the following nice little house that you may visit in 3D here.
